Well I booked another flight through the Cathay website tonight. When visiting the "Reservations Details" page, I am able to access the booking.

In the URL, there is the following syntax:
https://www.cathaypacific.com/xmlibe...&strLoc=XXXXXX

The XXXXXX reference is an Amadeus Trip number. Plugging that into www.checkmytrip.com gives me the flights. This is a pure CX flights only booking and is an electronic ticket.

Doesn't help of course if you don't already have online access to your booking. Suppose this gives it limited use. Would be a lot better if CX just had a generic "find your trip" page like most other airlines do...